In order to purify water contaminated by mineral oil or vegetable oil in factories and the like which use cooling water and rinse water, a processing method is commonly used in which aerobic bacteria, etc., is reacted in the waste water thereof and the contaminating components are dissolved from the aerobic bacteria, etc., being multiplied. In order to multiply aerobic bacteria, etc., in such types of waste water processing devices, it is necessary to provide an environment for the aerobic bacteria, etc., to survive by mixing microscopic bubbles in the waste water and encouraging aerobic respiration.
Devices which generate and mix microscopic bubbles in such types of waste water are called “aerators,” and are configured so as to mix waste water and air and to activate aerobic bacteria within the waste water, by being placed in the waste water to be purified. Conventionally, such aerators were constructed to be provided internally with a helical blade, and an upward stream, which was produced from airflow, was cast in whirlpool-like manner by such helical blades, etc., promoting the mixing of bubbles upstream.
In aerators provided with such blades, it is assumed that blockages are caused by foreign matter within the waste water getting caught on the blades. However, removing and cleaning, etc., such aerators provided internally with blades is generally difficult, and problematic in terms of maintenance.